Expandable fusion devices and methods of installation thereof

ABSTRACT

Exemplary embodiments of apparatuses and methods of an expandable fusion device are provided. In one embodiment, an intervertebral implant can be provided, having a first endplate having an upper surface and a lower surface, a second endplate having an upper surface and a lower surface. A first side wall extends from the first endplate and a second side wall extends from the second endplate and are configured to engage one another to provide a selective variable height between the first endplate and the second endplate. The first side wall and the second side wall form a substantially hollow portion substantially enclosed by the first endplate, second endplate and the side walls. The substantially hollow portion is configured to receive bone growth inducing material.

FIELD OF THE DISCLOSURE

The present disclosure relates to exemplary embodiments of systems,apparatuses and methods for promoting an intervertebral fusion, and moreparticularly, to exemplary embodiments of an expandable fusion devicecapable of being inserted between adjacent vertebrae to facilitate afusion process.

BACKGROUND INFORMATION

A common procedure for handling pain associated with intervertebraldiscs that have become degenerated due to various factors such as traumaor aging is the use of intervertebral fusion devices for fusing one ormore adjacent vertebral bodies. Generally, to fuse the adjacentvertebral bodies, the intervertebral disc is first partially or fullyremoved. An intervertebral fusion device is then typically insertedbetween neighboring vertebrae to maintain normal disc spacing andrestore spinal stability, thereby facilitating an intervertebral fusion.

There are a number of devices and methodologies in the art foraccomplishing intervertebral fusion. These include fusion devices whichinclude a cage or other implant mechanism, which can be packed with boneand/or bone growth inducing substances. These devices are implantedbetween adjacent vertebral bodies in order to fuse the vertebral bodiestogether, alleviating the associated pain.

However, there are drawbacks associated with these devices andmethodologies. For example, present methods for installing a fusiondevice often require that the adjacent vertebral bodies be distracted torestore a diseased disc space to its normal or healthy height prior toimplantation of the fusion device. In order to maintain this height oncethe fusion device is inserted, the fusion device is usually dimensionedlarger in height than the initial distraction height. This difference inheight can make it difficult for a surgeon to install the fusion devicein the distracted intervertebral space.

As such, there exists a need for a fusion device capable of beinginstalled inside an intervertebral disc space at a minimum height thatcan allow for bone growth inducing material within the fusion device toallow for fusion of the implant with the vertebral bodies. In addition,there is a need for providing secured fusion devices such thatadditional supplemental fixation may not be necessary, or at leastoptional.

At least one of the objects of the exemplary embodiments of the presentdisclosure is to reduce or address the deficiencies and/or limitationsof the prior art procedures and apparatuses described herein above, byproviding an intervertebral implant that does not suffer from thesedeficiencies.

SUMMARY OF EXEMPLARY EMBODIMENTS OF THE PRESENT DISCLOSURE

At least some of the above described problems can be addressed byexemplary embodiments of the apparatuses and methods according to thepresent disclosure. For example, using such exemplary embodiments, it ispossible to provide an expandable fusion device capable of beinginstalled inside an intervertebral disc space to maintain normal discspacing and restore spinal stability, thereby facilitating anintervertebral fusion, and providing a secured expandable fusion deviceso that posterior fixation may not be necessary.

In some exemplary embodiments, an intervertebral implant can beprovided, comprising a first endplate having an upper surface and alower surface, a second endplate having an upper surface and a lowersurface, and a side wall disposed between the first endplate and thesecond endplate and configured to have a selective height between thefirst endplate and the second endplate, wherein the side wall forms asubstantially hollow portion substantially enclosed by the firstendplate, second endplate and the side wall, and wherein thesubstantially hollow portion is configured to receive bone growthinducing material.

The side wall can comprise a first side wall extending from the lowersurface of the first endplate, and a second sidewall extending from theupper surface of the second endplate. The intervertebral implant canfurther comprise an engagement mechanism for engaging the first sidewallto the second sidewall and configured to provide a selective height ofthe sidewall between the first endplate and the second endplate. Theengagement mechanism can comprise a plurality of rails along a length ofan outer portion of the first sidewall from a proximal end to a distalend and a plurality of grooves along a length of an inner portion of thesecond sidewall from a proximal end to a distal end for selectiveengagement with the one or more rails. The first sidewall can comprise awall extending from a first side, a second opposing side and a distalend of the first endplate, and the second sidewall comprises a wallextending from a first side, a second opposing side and a distal end ofthe second endplate.

The intervertebral implant can further comprise an opening between aproximal end of the first endplate and a proximal end of the secondendplate configured to allow placement of an implant holder therein. Theintervertebral implant can further comprise an implant holder interfaceprovided along an outer portion of the second sidewall at opposing endsand configured to secure the intervertebral implant to an implantholder. The intervertebral implant can further comprise an end capinterface provided along an outer portion of the second sidewall atopposing ends. The intervertebral implant can further comprise an endcap secured to the end cap interface of the second sidewall engaging awall of the lower surface of the first endplate and the upper surface ofthe second endplate, the end cap configured to prevent displacement ofthe first endplate with respect to the second endplate. The end cap canseal the opening between the proximal end of the first endplate and theproximal end of the second endplate.

The intervertebral implant can further comprise a securing mechanism inthe end cap for securing the intervertebral implant to a vertebral bodyabove the first endplate and a vertebral body below the second endplate.The securing mechanism can further comprise a drive plate providedwithin the end cap, the drive plate comprising a first spike configuredto advance from the drive plate and engage with a vertebral body forsecuring the intervertebral implant to a vertebral body above the firstendplate, and a second spike configured to advance from the drive plateand engage with a vertebral body for securing the intervertebral implantto a vertebral body below the second endplate. The first and secondspikes can be configured to advance as a driver engaged with the driveplate is turned.

The substantially hollow portion can be configured for placement of acam, and configured to displace and engage the engagement mechanism asthe cam is rotated. The intervertebral implant can further comprise oneor more slots between the upper surface of the first endplate to thelower surface of the first endplate configured to allow fusion of bonegrowth inducing material within the intervertebral implant and avertebral body above the first endplate, and one or more slots extendingfrom the upper surface of the second endplate to the lower surface ofthe second endplate configured to allow fusion of bone growth inducingmaterial within the intervertebral implant and a vertebral body belowthe second endplate. The upper surface of the first endplate cancomprise texturing for engaging with a vertebral body and a lowersurface of the second endplate can comprise texturing for engaging witha vertebral body.

In some exemplary embodiments, an intervertebral implant can beprovided, comprising an upper endplate having a proximal end, a distalend, a first side and an opposing second side, a lower endplate having aproximal end, a distal end, a first side and an opposing second side, afirst sidewall extending along a periphery of the first side, distal endand second side of the upper endplate towards the lower endplate, asecond sidewall extending along a periphery of the first side, distalend and second side of the lower endplate towards the upper endplate,and an engagement mechanism for selective engagement of the firstsidewall with the second sidewall configured to provide a selectivedistance between the upper endplate and the lower endplate, wherein theupper endplate, lower endplate, first sidewall and second sidewallpartially enclose a substantially hollow portion configured to receivebone growth inducing material therein.

The intervertebral implant can further comprise an end cap secured tothe second sidewall engaging a wall of the upper endplate and the lowerendplate, the end cap configured to retain a selected height between theupper endplate and the lower endplate and seal an opening between theproximal ends of the upper endplate and the lower endplate. Theintervertebral implant can further comprise one or more slots in theupper endplate configured to allow fusion of bone growth inducingmaterial within the intervertebral implant and a vertebral body abovethe upper endplate, and one or more slots in the lower endplateconfigured to allow fusion of bone growth inducing material within theintervertebral implant and a vertebral body below the lower endplate.The engagement mechanism can comprise a plurality of rails along alength of an outer portion of the first sidewall from a proximal end toa distal end and a plurality of grooves along a length of an innerportion of the second sidewall from a proximal end to a distal end forselective engagement with the one or more rails.

In some exemplary embodiments, an intervertebral implant can beprovided, comprising a threaded shell configured to be placed within adisc space between vertebral bodies, an expansion mechanism within thethreaded shell configured to expand the threaded shell upon actuation,and an actuation mechanism configured to actuate the expansionmechanism.

The threaded shell can comprise an upper endplate, and a lower endplate;wherein the upper endplate and lower endplate separate and expand uponactuation of the actuation mechanism. The intervertebral implant canfurther comprise one or more graft windows within the threaded shellconfigured to allow bone growth inducing material to be placed withinthe threaded shell. The actuation mechanism can comprise a square nut.Rotation of the actuation mechanism in a first direction can expand thethreaded shell in an expanded state, and rotation of the actuationmechanism in a second direction can retract the threaded shell to anon-expanded state.

In some exemplary embodiments, a method of providing an intervertebralimplant can be provided, comprising drilling a hole within a disc spaceand a portion of a first vertebral body adjacent to the disc space at afirst end and a second vertebral body adjacent to the disc space at asecond opposite end, threading an expandable spacer including a threadedshell with an expansion mechanism enclosed within the threaded shellthrough the hole, and expanding the expandable spacer within the holeonce the expandable spacer is in position within the hole.

The method can further comprise actuating an actuation mechanism withinthe threaded shell to expand the expandable spacer within the hole. Thethreaded shell can comprise an upper endplate, and a lower endplate,wherein the upper endplate and lower endplate separate and expand uponactuation of the actuation mechanism.

In some embodiments, an intervertebral implant comprises a firstendplate having an upper surface and a lower surface, wherein the firstendplate comprises a first side wall that extends from the firstendplate; and a second endplate having an upper surface and a lowersurface, wherein the second endplate includes a second side wall thatextends from the second endplate; wherein the first side wall and thesecond side wall are configured to engage one another and provide aselective height between the first endplate and the second endplate;wherein the first side wall and the second side wall form asubstantially hollow portion substantially enclosed by the firstendplate, second endplate, first side wall and the second side wall; andwherein the substantially hollow portion is configured to receive bonegrowth inducing material.

In some embodiment, an intervertebral implant comprises an upperendplate having a proximal end, a distal end, a first side and anopposing second side; a lower endplate having a proximal end, a distalend, a first side and an opposing second side; a first sidewallextending along a periphery of the first side, distal end and secondside of the upper endplate towards the lower endplate; a second sidewallextending along a periphery of the first side, distal end and secondside of the lower endplate towards the upper endplate; and an engagementmechanism for selective engagement of the first sidewall with the secondsidewall configured to provide a selective distance between the upperendplate and the lower endplate; wherein the upper endplate, lowerendplate, first sidewall and second sidewall partially enclose asubstantially hollow portion configured to receive bone growth inducingmaterial therein.

These and other objects, features and advantages of the presentdisclosure will become apparent upon reading the following detaileddescription of embodiments of the present disclosure, when taken inconjunction with the appended claims. It should be understood that thedetailed description and specific examples, while indicating thepreferred or exemplary embodiments of the disclosure, are intended forpurposes of illustration only and are not intended to limit the scope ofthe disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other exemplary objects of the present disclosure willbe apparent upon consideration of the following detailed description,taken in conjunction with the accompanying exemplary drawings andclaims, in which like reference characters refer to like partsthroughout, and in which:

FIG. 1 illustrates a side perspective view of an intervertebral implantaccording to an exemplary embodiment of the present disclosure;

FIG. 2 illustrates a front perspective view of an intervertebral implantaccording to an exemplary embodiment of the present disclosure;

FIG. 3 illustrates a bottom perspective view of an upper endplate of anintervertebral implant according to an exemplary embodiment of thepresent disclosure;

FIG. 4 illustrates a top perspective view of a lower endplate of anintervertebral implant according to an exemplary embodiment of thepresent disclosure;

FIG. 5 illustrates a top perspective view of an implant holder with acam shaft according to an exemplary embodiment of the presentdisclosure;

FIG. 6 illustrates a side perspective view of an implant holder securedto an intervertebral implant according to an exemplary embodiment of thepresent disclosure;

FIG. 7 illustrates a cross-section of a front perspective view of a camwithin an intervertebral implant according to an exemplary embodiment ofthe present disclosure;

FIG. 8 illustrates a side perspective view of an implant holder securedto an intervertebral implant according to an exemplary embodiment of thepresent disclosure;

FIG. 9 illustrates a side perspective view of an intervertebral implantfilled with bone growth inducing material according to an exemplaryembodiment of the present disclosure;

FIG. 10 illustrates a side perspective view of an end cap according toan exemplary embodiment of the present disclosure;

FIG. 11 illustrates a side perspective view of an end cap engaged withan intervertebral implant according to an exemplary embodiment of thepresent disclosure;

FIG. 12 illustrates a side perspective view of an end cap secured to anintervertebral implant according to an exemplary embodiment of thepresent disclosure;

FIG. 13 illustrates a side perspective view of an end cap with spikesaccording to an exemplary embodiment of the present disclosure;

FIG. 14 illustrates a cross-section of a side perspective view of adrive plate of an end cap according to an exemplary embodiment of thepresent disclosure;

FIG. 15 illustrates a side perspective view of a driver within a driveplate of an end cap according to an exemplary embodiment of the presentdisclosure;

FIG. 16 illustrates a side perspective view of a driver turning within adrive plate of an end cap according to an exemplary embodiment of thepresent disclosure;

FIG. 17 illustrates a side perspective view of an end cap with spikesaccording to an exemplary embodiment of the present disclosure;

FIG. 18 illustrates a side perspective view of an end cap with a driveplate engaged to an intervertebral implant according to an exemplaryembodiment of the present disclosure;

FIG. 19 illustrates a side perspective view of an end cap with a driveplate secured to an intervertebral implant according to an exemplaryembodiment of the present disclosure;

FIG. 20 illustrates a side perspective view of an end cap with spikesengaged to an intervertebral implant according to an exemplaryembodiment of the present disclosure;

FIG. 21 illustrates a side view of an end cap with spikes secured to anintervertebral implant according to an exemplary embodiment of thepresent disclosure;

FIG. 22 illustrates a side perspective side view of an end cap withscrews according to an exemplary embodiment of the present disclosure;

FIG. 23 illustrates a side perspective view of an end cap engaged to anintervertebral implant according to an exemplary embodiment of thepresent disclosure;

FIG. 24 illustrates a side perspective view of an end cap secured to anintervertebral implant according to an exemplary embodiment of thepresent disclosure;

FIG. 25 illustrates a side perspective view of an end cap with screwssecured to an intervertebral implant according to an exemplaryembodiment of the present disclosure;

FIG. 26 illustrates a perspective view of a disc space between twovertebral bodies according to an exemplary embodiment of the presentdisclosure;

FIG. 27 illustrates a perspective view of a drill within a disc spacebetween two vertebral bodies according to an exemplary embodiment of thepresent disclosure;

FIG. 28 illustrates a perspective view of a drill within an endoscopictube according to an exemplary embodiment of the present disclosure;

FIG. 29 illustrates a perspective view of an expandable spacer beingthreaded in a drill hole between two vertebral bodies according to anexemplary embodiment of the present disclosure;

FIG. 30 illustrates a perspective view of an expandable spacer within adrill hole between two vertebral bodies according to an exemplaryembodiment of the present disclosure;

FIG. 31 illustrates a perspective view of an expandable spacer in anon-expanded state according to an exemplary embodiment of the presentdisclosure;

FIG. 32 illustrates a perspective view of an expandable spacer in anexpanded state according to an exemplary embodiment of the presentdisclosure;

FIG. 33 illustrates a cross-section of a side view of an expandablespacer in a non-expanded state within a disc space according to anexemplary embodiment of the present disclosure; and

FIG. 34 illustrates a cross-section of a side view of an expandablespacer in an expanded state within a disc space according to anexemplary embodiment of the present disclosure.

FIG. 35 shows a close up view of a rail.

FIG. 36 shows a close up view of grooves.

Throughout the figures, the same reference numerals and characters,unless otherwise stated, are used to denote like features, elements,components or portions of the illustrated embodiments. Moreover, whilethe subject disclosure will now be described in detail with reference tothe figures, it is done so in connection with the illustrativeembodiments. It is intended that changes and modifications can be madeto the described embodiments without departing from the true scope andspirit of the subject disclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF DISCLOSURE

Exemplary embodiments of the apparatuses and methods of the presentdisclosure will now be described with reference to the figures. Thefollowing description of the various embodiments is merely exemplary innature and is in no way intended to limit the scope of the disclosure,its application, or uses.

A spinal fusion is typically employed to eliminate pain caused by themotion of degenerated disk material. Upon successful fusion, a fusiondevice becomes fixed within the intervertebral disc space. The presentdisclosure advantageously provides novel fusion devices that can beinserted in a first height and expanded to a second height that isgreater than the first height. Advantageously, the fusion devicesinclude novel expansion mechanisms that can expand the devices in asteady and controlled manner.

Referring to FIGS. 1-4, in some embodiments, an intervertebral implant100 is provided comprising an upper endplate 110 and a lower endplate150. The upper endplate 110 and lower endplate 150 can be manufacturedfrom a number of materials including titanium, stainless steel, titaniumalloys, non-titanium metallic alloys, polymeric materials, plastics,plastic composites, PEEK, PEEK with a titanium spray, ceramic, andelastic materials. In some embodiments, nitinol can be used as amaterial. In some embodiments, an HA coating can be applied to theendplates. In some embodiments, the intervertebral implant 100 can beconfigured to be placed down an endoscopic tube and into the disc spacebetween adjacent vertebral bodies.

In some embodiments, the upper endplate 110 can have a proximal end 122,a distal end 124, a first side 126, a second side 128 opposite to thefirst side 126, an upper surface 112 and a lower surface 114. The lowerendplate 150 can have a proximal end 162, a distal end 164, a first side166, a second side 168 opposite to the first side 166, an upper surface152 and a lower surface 154. The upper surface 112 of the upper endplate110 and the lower surface 154 of the lower endplate 150 can includetexturing to aid in gripping the adjacent vertebral bodies. Although notlimited to the following, the texturing can include teeth, ridges,friction increasing elements, keels, or gripping or purchasingprojections.

In some embodiments, the upper endplate 110 can have one or more slots116 configured to allow fusion of bone growth inducing material withinthe intervertebral implant 100 and an adjacent vertebral body. In someembodiments, the upper endplate 110 can have two slots 116 on oppositesides of a middle portion 146 of the upper endplate 110. The upperendplate 110 can have a sidewall 160 extending from the lower surface114 having a first side portion 134 at a first side 126 of the upperendplate 110, a second side portion 132 at a second side 128 of theupper endplate 110, and a distal portion 136 at a distal end 124 of theupper endplate 110. Although the sidewall 160 is shown as integral withthe upper endplate 110, the sidewall 160 can be separate from the upperendplate 110 in some embodiments, and can be releasably engaged with theupper endplate 110 in some embodiments. The sidewall 160 can extendalong an inner periphery of the first side 126, distal end 124 and thesecond side 128 of the upper endplate 110. In other embodiments, theupper endplate 110 can comprise a pair of sidewalls independent from oneanother, such that a first sidewall extends along a first side 126 ofthe upper endplate 110 and a second sidewall extends along a second side128 of the upper endplate. In some embodiments, the sidewall 160 canhave one or more rails 140 (shown in FIG. 35) provided along a length ofthe sidewall 160 and parallel to the upper endplate 110. The rails 140can be provided along a length of the first side portion 134 and thesecond side portion 132 of the sidewall 160. In some embodiments, theone or more rails 140 are aligned vertically, one on top of the other.

In some embodiments, the lower endplate 150 can have one or more slots156 configured to allow fusion of bone growth inducing material withinthe intervertebral implant 100 and an adjacent vertebral body. In someembodiments, the lower endplate 150 can have two slots 156 on oppositesides of a middle portion 186 of the lower endplate 150. The lowerendplate 150 can have a sidewall 170 extending from the upper surface152 having a first side portion 174 at a first side 166 of the lowerendplate 150, a second side portion 172 at a second side 168 of thelower endplate 150, and a distal portion 176 at a distal end 164 of thelower endplate 150. Although the sidewall 170 is shown as integral withthe lower endplate 150, the sidewall 170 can be separate from the lowerendplate 150 in some embodiments, and can be releasably engaged with thelower endplate 150 in some embodiments. The sidewall 170 can extendalong an inner periphery of the first side 166, distal end 164 and thesecond side 168 of the lower endplate 150. In other embodiments, thelower endplate 150 can comprise a pair of sidewalls independent from oneanother, such that a first sidewall extends along a first side 166 ofthe lower endplate 110 and a second sidewall extends along a second side168 of the lower endplate. In some embodiments, the sidewall 170 canhave one or more grooves 190 (shown in FIG. 36) provided along a lengthof the sidewall 170 and parallel to the lower endplate 150. The grooves190 can be provided along a length of the first side portion 174 and thesecond side portion 172 of the sidewall 170. In some embodiments, theone or more grooves 190 are aligned vertically, one on top of the other.

In some embodiments, the rails 140 of the sidewall 160 can correspond tothe grooves of the sidewall 170, allowing engagement of the sidewall 160of the upper endplate 110 with the sidewall 170 of the lower endplate150. In some embodiments, the rails 140 and grooves 190 can be providedalong one millimeter intervals, and can range from 0.2 millimeterintervals to 6 millimeter intervals. In other embodiments, the rails 140and grooves 190 can be provided at less than one millimeter intervals,or greater than one millimeter intervals. This can provide for selectiveengagement of the rails 140 with the grooves 190, which can provide forvariable heights between the upper endplate 110 and the lower endplate150. This can provide for expansion of the intervertebral implant 100(e.g., via an instrument as shown in FIG. 5) as may be necessary, aswill be described below. In some embodiments, a substantially hollowportion 192 is provided between the engaged sidewalls 160, 170. Thehollow portion can be used to pack bone graft or similar bone growthinducing material within the intervertebral implant 100. This canadvantageously provide for stronger fusion of the intervertebral implant100 with adjacent vertebral bodies. The sidewalls can provide forcomplete enclosure along the side portions of the endplates and thedistal ends of the endplates, and provide an opening 158 between theproximal ends of the endplates. For example, the sidewalls 160 and 170can provide for complete enclosure between the first side 126 of theupper endplate 110 and the first side 166 of the lower endplate 150, thesecond side 128 of the upper endplate 110 and the second side 168 of thelower endplate 150, and the distal end 124 of the upper endplate 110 andthe distal end 164 of the lower endplate 150. An opening 158 can beprovided between the proximal end 122 of the upper endplate 110 and theproximal end 162 of the lower endplate 150.

In some embodiments, the upper endplate 110 can have grooves and thelower endplate 150 can have rails. Other engagement mechanisms can alsobe used, such as a pin within a slot, clips, fasteners, other mechanicalmechanisms, magnets, or any other attachment mechanisms and the presentdisclosure is not limited to any particular type of engagement mechanismbetween the upper and lower endplates.

In some embodiments, the sidewall 170 can have an implant holderinterface 178 for engagement with an implant holder, as will bediscussed below. The implant holder interface 178 can be but is notlimited to a groove, hole, ridge or other engagement mechanism. Theimplant holder interface 178 can be provided along the first sideportion 174 and the second side portion 172 of the sidewall 170. Thesidewall 170 can have an end cap interface 180 for engagement with anend cap, as will be discussed below. The end cap interface 180 can bebut is not limited to a groove, hole, ridge or other engagementmechanism. The end cap interface 180 can be provided along the firstside portion 174 and the second side portion 172 of the sidewall 170.

Referring to FIGS. 5-8, in some embodiments, an implant holder 200 isprovided that can be used to deliver the intervertebral implant 100 andraise the upper endplate 110 with respect to the lower endplate 150. Insome embodiments, the implant holder 200 can have inner implantinterfacing tangs 210 and 212, outer implant interfacing tangs 220 and222, and cam shaft 230, which can be placed in the center of theinterfacing tangs. Outer implant interfacing tangs 220 and 222 can belonger than the inner interfacing tangs 210 and 212. Cam shaft 230 canbe connected to a middle tang 232.

In some embodiments, the implant holder 200 can be inserted within theopening 158 between the proximal end 122 of the upper endplate 110 andthe proximal end 162 of the lower endplate 150, such that outer implantinterfacing tangs 220 and 222 are placed outside of the first sideportion 174 and second side portion 172 of the lower endplate 150,respectively. The inner implant interfacing tangs 210 and 212 can beplaced inside of the first side portion 134 and the second side portion132 of the upper endplate 110. The cam 230 can be placed underneath amiddle portion 146 of the upper endplate 110 and middle portion 186 ofthe lower endplate 150.

In some embodiments, as the cam 230 is turned, it presses against themiddle portion 146 of the upper endplate 110 and middle portion 186 ofthe lower endplate 150, raising the upper endplate 110 with respect tothe lower endplate 150. As the upper endplate 110 rises, the engagementrails 140 snap out of their respective grooves 190 and snap back in tothe next corresponding grooves 190. When the desired height of the upperendplate 110 with respect to the lower endplate 150 is achieved, the cam230 can be turned back and the implant holder 200 can be removed fromthe intervertebral implant 100. In some exemplary embodiments, the cam230 can be built inside the intervertebral implant 100, and the implantholder 200 can have an instrument to engage the cam 230 and turn the cam230.

Referring to FIG. 9, in some embodiments, after the intervertebralimplant 100 has been expanded, bone graft or similar bone growthinducing material 250 can be placed within the intervertebral implant100 through, e.g., opening 158 between the upper endplate 110 and thelower endplate 150. In some exemplary embodiments, bone graft or similarbone growth inducing material 250 can be introduced around and withinthe intervertebral implant 100 to further promote and facilitate theintervertebral fusion. The intervertebral implant 100, in someembodiments, can be packed with bone graft or similar bone growthinducing material to promote the growth of bone through and around theintervertebral implant 100. Some amount of bone graft may also be packedbetween the endplates of the adjacent vertebral bodies prior to,subsequent to, or during implantation of the fusion device. Some bonegraft may also be packed within the intervertebral implant 100 beforeinsertion into the disc space between the vertebral bodies. Slots 116and 156 can help promote fusion by allowing the bone growth inducingmaterial 250 to exude out of the respective slots and engage with thevertebral bodies engaged with upper endplate 110 and lower endplate 150.

Referring to FIGS. 10-12, in some embodiments, an end cap 300 can beprovided having rails 310 and 312. The end cap 300 can be made of thesame material as the upper endplate 110 and lower endplate 150. The endcap 300 can have a locking interface 320 on the rail 310 to engage withthe end cap interface 180 of the first side portion 174 of sidewall 170,and a locking interface 320 on the rail 312 to engage with the end capinterface 180 of the second side portion 172 of the sidewall 170. Oncethe locking interfaces 320 are secured in place with the end capinterfaces 180, the end cap 300 can seal the opening 158 between theupper endplate 110 and the lower endplate 150. The end cap 300 can beselected so that the height h of the rails 310 and 312 correspond to theheight between the upper endplate 110 and the lower endplate 150. Therails 310 and 312 can engage a lower surface of the upper endplate 110and an upper surface of the lower endplate 150, providing extra supportbetween the upper endplate 110 and the lower endplate 150, and helpingmaintain the height between the upper endplate 110 and the lowerendplate 150.

In some exemplary embodiments, the height h of the rails 310 and 312 canbe slightly greater than the distance between the upper endplate 110 andthe lower endplate 150, and can provide extra support and help raise theupper endplate 110 with respect to the lower endplate 150 even farther.For example, the distance between the upper endplate 110 and the lowerendplate 150 can be four millimeters, and an end cap with a height h offive millimeters of the rail 310 can be used to raise the upper endplate110 with respect to the lower endplate 150.

Referring to FIGS. 13-17, in some exemplary embodiments, a drive plate330 can be provided on the end cap 300. The drive plate 330 can have oneor more openings, such as opening 332 and opening 342, and one or morespikes, such as spike 340 and spike 342. The spikes 340 and 342 can bemade of the same material as the upper endplate 110 and lower endplate150. In some embodiments, the spikes 340 and 342 can have ridges andgrooves that extend along or from an elongated body. In addition, insome embodiments, the spikes 340 and 342 can comprise a spherical head.Advantageously, the spikes 340 and 342 can be inserted into a vertebralbody to help secure the vertebral implant 100 to the vertebral bodies.The opening 332 can be provided closer to the lower endplate 150 and theopening 334 can be provided closer to the upper endplate 110. The driveplate 330 can have a thread hole 352 at a proximal portion of the driveplate 330. A driver 350 can be used and threaded into the thread hole352. When the driver is turned in a first direction (e.g.,counterclockwise), the distal portion of the drive plate 330 is pushedaway from the proximal portion of the drive plate 330, and the spikes340 and 342 are advanced out of the openings 332 and 334, respectively.Turning the driver 350 in a second direction (e.g., clockwise) canretract the spikes 340 and 342 back into the openings 332 and 334.

Referring to FIGS. 18-21, in some exemplary embodiments, the end cap 300can engage with a vertebral implant 100 as discussed above. Once the endcap 300 is secured and the vertebral implant 100 is in place, a driver350 can be inserted into the thread hole 352 and turned to advance thespikes 340 and 342. The spike 340 can be advanced in a first directionand driven into a vertebral body below the lower endplate 150, and thespike 342 can be advanced in a second direction and driven into avertebral body above the upper endplate 110. This can help secure thevertebral implant 100 to the vertebral bodies so that posterior fixationor other procedures are not necessary to secure the vertebral implant100 to the vertebral bodies.

Referring to FIGS. 22-25, in some exemplary embodiments, an end cap 300can be provided with openings 30 and 362 with screws 370 and 372,respectively. Once the end cap 300 is secured and the vertebral implant100 is in place, the screw 370 can be advanced in a first directionthrough opening 360 and driven into a vertebral body above the upperendplate 110, and the screw 372 can be advanced in a second directionand driven into a vertebral body below the lower endplate 150. This canhelp secure the vertebral implant 100 to the vertebral bodies so thatposterior fixation or other procedures are not necessary to secure thevertebral implant 100 to the vertebral bodies.

In additional embodiments, a threaded expandable spacer can be providedthat can expand in-situ. By providing a threaded expandable spacer 400,this helps to decrease migration and subsidence. Furthermore, thethreaded expandable spacer advantageously provides maximum amount ofcontact surface area, thereby increasing purchase into adjacentvertebral bodies. Furthermore, the threaded expandable spacer can workon its own, such that supplemental fixation (e.g., posterior fixation)may not be necessary and can be optional.

Referring to FIGS. 26-30, a disc space 406 is shown between vertebralbody 402 and vertebral body 404. A drill 412 can be inserted through anendoscopic tube 410 to drill a hole 408 within the disc space 406, andwithin the vertebral bodies 402 and 404. That is, the drill diameter isa little larger than the height of the disc space 406 such that aportion of the vertebral bodies 402 and 404 is also drilled. Once thehole 408 is drilled, an endoscopic tube 410 can be used to deliver athreaded expandable spacer 400 into the drill hole 408. The threadedexpandable spacer 400 can have a shell 435 and threads 420 on the shell435, and a nut 430 or other mechanism for engagement on a proximal end422 of the threaded expandable spacer 400. An actuation mechanism can beused to engage the nut 430 so that it can be turned to turn the threadedexpandable spacer 400 and drive the threads 420 of the threadedexpandable spacer 400 into the drill hole 408. In some embodiments, thediameter of the drill 412 can be slightly less than the diameter of thethreaded expandable spacer 400, so that the threaded expandable spacer400 is fit tightly into the drill hole 408 as it is threaded into thedrill hole 408 and disc space 406.

Referring to FIGS. 31-32, in some embodiments, the threaded expandablespacer 400 can include a distal end 424 and a proximal end 422. The nut430 can be provided at the proximal end 422. Threads 420 can be providedalong an outer periphery of the threaded expandable spacer 400. In someexemplary embodiments, the shell 435 of the threaded expandable spacer400 has an upper endplate 450 and a lower endplate 460. The threads 420are provided on both the upper endplate 450 and the lower endplate 460such that they are continuous when the threaded expandable spacer 400 isin a non-expanded state (e.g., FIG. 31). One or more graft windows 440can be provided to provide bone graft or similar bone growth inducingmaterial to help fuse the threaded expandable spacer 400 with thevertebral bodies.

In some exemplary embodiments, the upper endplate 450 and the lowerendplate 460 can move with respect to each other to expand in anexpanded state (e.g., FIG. 32). The nut 430, which can be a square nut,can be connected to expansion mechanism 470 and have an upper and lowerramp that mate with opposing ramps on the inside of the endplates, as isdescribed in U.S. Pat. No. 8,845,731, which is incorporated by referencein its entirety. With the exception of the type of endplates describedin U.S. Pat. No. 8,845,731, a similar expansion mechanism can be usedfor expansion mechanism 470, with endplates 450 and 460. As the nut 430is actuated (e.g., by turning the threaded shaft in a first direction),the ramps force the endplates 450 and 460 away from the center of thethreaded expandable spacer 400. The nut 430 can have pins to help retainthe endplates 450 and 460. When the threaded shaft is turned in a seconddirection (i.e., opposite the first direction), the endplates 450 and460 can retract back to the center of the threaded expandable spacer 400to a non-expanded state.

Referring to FIGS. 33-34, in some embodiments, the threaded expandablespacer 400 can be provided within a drill hole 408 in a disc space 406between adjacent vertebral bodies 402 and 404 in a non-expanded state(e.g., FIG. 33). The threaded expandable spacer 400 can be turned sothat the upper endplate 450 would expand towards the vertebral body 402when expanded, and the lower endplate 460 would expand towards thevertebral body 404 when expanded. The nut 430 can be actuated to movethe upper endplate 450 and lower endplate 460 away from the center ofthe threaded expandable spacer 400. The threaded expandable spacer 400can be expanded in-situ. Graft windows 440 can be provided in both theupper endplate 450 and the lower endplate 460 to provide bone graft orsimilar bone growth inducing material within the threaded expandablespacer 400 to help promote fusion between the threaded expandable spacer400 and the adjacent vertebral bodies 402 and 404. The threads 420 ofthe threaded expandable spacer 400 can secure the threaded expandablespacer 400 within the disc space 406 and within the vertebral bodies 402and 404 such that posterior fixation may not be necessary, and anymigration of the threaded expandable spacer 400 can be prevented. Thethreaded expandable spacer 400 can be threaded inside the cancellousregion of the vertebral bodies, which can promote faster bone growth andyield a maximum amount of contact surface area into both adjacentvertebral bodies 402 and 404, as well as reduce the chance of backingout or migrating.

In some exemplary embodiments, in the event the threaded expandablespacer 400 needs to be repositioned or revised after being installed andexpanded, the threaded expandable spacer 400 can be contracted back tothe unexpanded configuration, repositioned, and expanded again once thedesired positioning is achieved. To contract the threaded expandablespacer 400, an instrument can be used to rotate the actuator assembly(as described in U.S. Pat. No. 8,845,731), which can move the endplates450 and 460 inwardly into the unexpanded position. Various differenttypes of expansion mechanisms can be used within the endplates 450 and460, and the present disclosure is not limited to any particular type ofexpansion mechanism.

Various delivery methods and devices can be used to deliver the fusiondevices described in the present disclosure. For example, prior toinsertion of the fusion devices described herein, the intervertebralspace can be prepared. In one method of installation, a discectomy isperformed where the intervertebral disc, in its entirety, can beremoved. Alternatively, only a portion of the intervertebral disc can beremoved. The endplates of adjacent vertebral bodies can be scraped tocreate an exposed end surface for facilitating bone growth across theintervertebral space. One or more endoscopic tubes can then be insertedinto the disc space. The expandable fusion device can then be introducedinto the intervertebral space down an endoscopic tube and seated in anappropriate position in the intervertebral disc space.

Various configurations of the expandable fusion devices are contemplatedand are not limited by the embodiments described with reference to thefigures. For example, various sizes, shapes and types of endplates arecontemplated, and various materials can be used to construct the variousparts, such as the endplates, end caps, drive plates and spikesdescribed herein. The exemplary embodiments of the present disclosureprovide various advantages, such as being able to be expanded in-situ.The intervertebral implant described herein can provide a substantiallyhollow portion between the endplates to allow a significant amount ofbone graft or similar bone growth inducing material to be placed thereinto allow maximum fusion of the bone growth inducing material within theintervertebral implant and the adjacent vertebral bodies. Although thepreceding discussion only discussed having a single fusion device in theintervertebral space, it is contemplated that more than one fusiondevice can be inserted in the intervertebral space. It is furthercontemplated that each fusion device does not have to be finallyinstalled in the fully expanded state. Rather, depending on the locationof the fusion device in the intervertebral disc space, the height of thefusion device may vary from unexpanded to fully expanded. It should benoted that, as well as the height being varied from an unexpanded stateto an expanded state, the fusion may be positioned permanently anywherebetween the expanded state and the unexpanded state.

In some embodiments, the fusion devices described above can beaccompanied with other devices, including but not limited to rods, screw(e.g., pedicle screws), plates, and other stabilization devices. Inaddition, while any of the devices described above can be used on asingle level, a multi-level procedure can be performed using multiplesimilar device, or using one device with a different device. Forexample, it is possible to use any of the fusion devices described abovein one level, while having a prosthetic implant on another level.

The foregoing merely illustrates the principles of the disclosure.Various modifications and alterations to the described embodiments willbe apparent to those skilled in the art in view of the teachings herein.It will thus be appreciated that those skilled in the art will be ableto devise numerous apparatuses, arrangements, manufacture and methodswhich, although not explicitly shown or described herein, embody theprinciples of the disclosure and are thus within the spirit and scope ofthe disclosure. The disclosures of all documents and publications citedherein are hereby incorporated herein by reference in their entireties.

What is claimed is:
 1. An intervertebral implant, comprising: a firstendplate having an upper surface and a lower surface, wherein the firstendplate comprises a first side wall that extends from the firstendplate; and a second endplate having an upper surface and a lowersurface, wherein the second endplate includes a second side wall thatextends from the second endplate; wherein the first side wall and thesecond side wall are configured to engage one another and provide aselective height between the first endplate and the second endplate;wherein the first side wall and the second side wall form asubstantially hollow portion substantially enclosed by the firstendplate, second endplate, first side wall and the second side wall; andwherein the substantially hollow portion is configured to receive bonegrowth inducing material.
 2. The intervertebral implant of claim 1,wherein the first side wall is integral with the first endplate and thesecond side wall is integral with the second endplate.
 3. Theintervertebral implant of claim 1, further comprising: an engagementmechanism for engaging the first sidewall to the second sidewall andconfigured to provide a selective height between the first endplate andthe second endplate.
 4. The intervertebral implant of claim 3, whereinthe engagement mechanism comprises a plurality of rails along a lengthof an outer portion of the first sidewall from a proximal end to adistal end and a plurality of grooves along a length of an inner portionof the second sidewall from a proximal end to a distal end for selectiveengagement with the one or more rails.
 5. The intervertebral implant ofclaim 4, wherein the first sidewall comprises a wall extending from afirst side, a second opposing side and a distal end of the firstendplate, and the second sidewall comprises a wall extending from afirst side, a second opposing side and a distal end of the secondendplate.
 6. The intervertebral implant of claim 5, further comprising:an opening between a proximal end of the first endplate and a proximalend of the second endplate configured to allow placement of an implantholder therein.
 7. The intervertebral implant of claim 6, furthercomprising: an implant holder interface provided along an outer portionof the second sidewall at opposing ends and configured to secure theintervertebral implant to an implant holder.
 8. The intervertebralimplant of claim 6, further comprising: an end cap interface providedalong an outer portion of the second sidewall at opposing ends.
 9. Theintervertebral implant of claim 8, further comprising: an end capsecured to the end cap interface of the second sidewall engaging a wallof the lower surface of the first endplate and the upper surface of thesecond endplate, the end cap configured to prevent displacement of thefirst endplate with respect to the second endplate.
 10. Theintervertebral implant of claim 9, wherein the end cap seals the openingbetween the proximal end of the first endplate and the proximal end ofthe second endplate.
 11. The intervertebral implant of claim 10, furthercomprising: a securing mechanism in the end cap for securing theintervertebral implant to a vertebral body above the first endplate anda vertebral body below the second endplate.
 12. The intervertebralimplant of claim 11, wherein the securing mechanism comprises: a driveplate provided within the end cap, the drive plate comprising a firstspike configured to advance from the drive plate and engage with avertebral body for securing the intervertebral implant to a vertebralbody above the first endplate, and a second spike configured to advancefrom the drive plate and engage with a vertebral body for securing theintervertebral implant to a vertebral body below the second endplate.13. The intervertebral implant of claim 12, wherein the first and secondspikes are configured to advance as a driver engaged with the driveplate is turned.
 14. The intervertebral implant of claim 4, wherein thesubstantially hollow portion is configured for placement of a cam, andconfigured to displace and engage the engagement mechanism as the cam isrotated.
 15. The intervertebral implant of claim 1, further comprising:one or more slots between the upper surface of the first endplate to thelower surface of the first endplate configured to allow fusion of bonegrowth inducing material within the intervertebral implant and avertebral body above the first endplate; and one or more slots extendingfrom the upper surface of the second endplate to the lower surface ofthe second endplate configured to allow fusion of bone growth inducingmaterial within the intervertebral implant and a vertebral body belowthe second endplate.
 16. The intervertebral implant of claim 1, whereinan upper surface of the first endplate comprises texturing for engagingwith a vertebral body and a lower surface of the second endplatecomprises texturing for engaging with a vertebral body.
 17. Anintervertebral implant, comprising: an upper endplate having a proximalend, a distal end, a first side and an opposing second side; a lowerendplate having a proximal end, a distal end, a first side and anopposing second side; a first sidewall extending along a periphery ofthe first side, distal end and second side of the upper endplate towardsthe lower endplate; a second sidewall extending along a periphery of thefirst side, distal end and second side of the lower endplate towards theupper endplate; and an engagement mechanism for selective engagement ofthe first sidewall with the second sidewall configured to provide aselective distance between the upper endplate and the lower endplate;wherein the upper endplate, lower endplate, first sidewall and secondsidewall partially enclose a substantially hollow portion configured toreceive bone growth inducing material therein.
 18. The intervertebralimplant of claim 17, further comprising: an end cap secured to thesecond sidewall engaging a wall of the upper endplate and the lowerendplate, the end cap configured to retain a selected height between theupper endplate and the lower endplate and seal an opening between theproximal ends of the upper endplate and the lower endplate.
 19. Theintervertebral implant of claim 17, further comprising: one or moreslots in the upper endplate configured to allow fusion of bone growthinducing material within the intervertebral implant and a vertebral bodyabove the upper endplate; and one or more slots in the lower endplateconfigured to allow fusion of bone growth inducing material within theintervertebral implant and a vertebral body below the lower endplate.20. The intervertebral implant of claim 17, wherein the engagementmechanism comprises a plurality of rails along a length of an outerportion of the first sidewall from a proximal end to a distal end and aplurality of grooves along a length of an inner portion of the secondsidewall from a proximal end to a distal end for selective engagementwith the one or more rails.